112 STEMS 



106. STEMS 

 Object. Same as in Experiments 104 ana 105. 



Method. Prepare two sets of seeds by letting them ger- 

 minate in a box of good soil. 



As soon as the sprouts peep above the soil, place the box 

 in a position where heat, water, and air supply will be favor- 

 able for growth, but not in direct sunlight. Now cover some 

 of the plants by placing over them an inverted flowerpot 

 whose drain hole is corked tight. Push the flowerpot down 

 far enough to prevent any light from getting in below. The 

 plants will thus be placed in exactly similar conditions 

 except light. 



From time to time examine and measure length of nodes 

 and size of leaves. Note also the color of stem and leaves, 

 and the vigor of stem. Remove the inverted flowerpot and 

 exppse the plants to the light. 



After three days look for changes in color, vigor, etc. 



Turn over a flat stone or board which has lain for some time 

 on the ground. How have plants been affected where light 

 was excluded ? 



Note. The preceding exercises are equally good to demon- 

 strate the effects of light on roots. 



Suggestion. Cut off a stem of wheat or any other cereal 

 long enough to have at least one node. Pass it through a 

 cork into a flat bottle partly full of water and lay the bottle 

 on its side so that the cut end of the stem is under the sur- 

 face of the water. Stand the whole in a dark place for 

 several hours. What is the result? Why? 



For city schools any of the common tall grasses found 

 growing in waste places are equally good for this work. 



